<!DOCTYPE html>
<html>
  <head>
    <title>Histogram</title>
    <script type="text/javascript" src="../../d3.js"></script>
    <script type="text/javascript" src="../../d3.layout.js"></script>
    <style type="text/css">

body {
  font: 10px sans-serif;
}

rect {
  fill: steelblue;
  stroke: white;
}

line {
  stroke: black;
  shape-rendering: crispEdges;
}

    </style>
  </head>
  <body>
    <script type="text/javascript">

var n = 10000, // number of trials
    m = 10,    // number of random variables
    data = [];

// Generate an Irwin-Hall distribution.
for (var i = 0; i < n; i++) {
  for (var s = 0, j = 0; j < m; j++) {
    s += Math.random();
  }
  data.push(s);
}

var w = 400,
    h = 400;

var histogram = d3.layout.histogram()
    (data);

var x = d3.scale.ordinal()
    .domain(histogram.map(function(d) { return d.x; }))
    .rangeRoundBands([0, w]);

var y = d3.scale.linear()
    .domain([0, d3.max(histogram, function(d) { return d.y; })])
    .range([0, h]);

var vis = d3.select("body").append("svg")
    .attr("width", w)
    .attr("height", h)
  .append("g")
    .attr("transform", "translate(.5)");

vis.selectAll("rect")
    .data(histogram)
  .enter().append("rect")
    .attr("transform", function(d) { return "translate(" + x(d.x) + "," + (h - y(d.y)) + ")"; })
    .attr("width", x.rangeBand())
    .attr("y", function(d) { return y(d.y); })
    .attr("height", 0)
  .transition()
    .duration(750)
    .attr("y", 0)
    .attr("height", function(d) { return y(d.y); });

vis.append("line")
    .attr("x1", 0)
    .attr("x2", w)
    .attr("y1", h)
    .attr("y2", h);

    </script>
  </body>
</html>
